Soldier. Williamson immigrated to Ninety Six District from his native Scotland. He was earning a living as a cattle driver by 1758 and was commissioned as a lieutenant in the South Carolina Provincial Regiment of Foot during the Cherokee War of 1760–1761. At the end of the war he was awarded the contract to supply provisions to backcountry garrisons. By 1767 he had acquired a large plantation, White Hall, on Hard Labor Creek (present-day Greenwood County) and lived there with his family.
An ardent patriot at the outbreak of the Revolutionary War, Williamson held the rank of major in the militia of Ninety Six District and represented the area in the First and Second Provincial Congresses. Williamson’s arrest of the Tory leader Robert Cunningham provoked British sympathizers in the region, and on November 19, 1775, a large Loyalist force attacked his patriot force, who had thrown up a hastily constructed fort at Ninety Six. After several days of intermittent fighting, both sides agreed to a truce. Reinforced by patriot soldiers under Colonel Richard Richardson, Williamson continued to pursue and detain Loyalist leaders in the following weeks in what was to become the Snow Campaign.
At the behest of William Henry Drayton, Williamson was promoted to the rank of colonel in 1776 and charged with conducting a punitive expedition against British-allied Native Americans on the frontier. The campaign subdued the Cherokees, who signed a treaty at DeWitt’s Corner on May 20, 1777, that ceded practically all of their lands in South Carolina. Williamson had been promoted to the rank of brigadier general by 1778 and commanded the South Carolina militia in Major General Robert Howe’s disastrous Florida expedition that summer. In September–October of the following year he participated in the unsuccessful siege of Savannah.
Williamson’s actions in the days surrounding the capture of Charleston led many to conclude that he had “turned coat.” He accepted British protection and retired to White Hall. Though pressed on two occasions to renounce his parole, Williamson feared for his family and accepted British protection in Charleston, where he did serve as a double agent for Continental forces. Because of this, Williamson was allowed to stay in South Carolina after the war. He died at his plantation in St. Paul’s Parish, near Charleston, on March 21, 1786.
Cann, Marvin L. “Prelude to War: The First Battle of Ninety-Six, November 19–21, 1775.” South Carolina Historical Magazine 76 (October 1975): 197–214.
Johnson, Joseph. Traditions and Reminiscences, Chiefly of the American Revolution in the South. 1851. Reprint, Spartanburg, S.C.: Reprint Company, 1972.
Lumpkin, Henry. From Savannah to Yorktown: The American Revolution in the South. Columbia: University of South Carolina Press, 1981.